Electron-discharge amplifier



Dec. v 1,520,994

H. DI ARNOLD ELECTRON DISCHARGE AMPLIFIER Original Filed Sept. 5, 1915 //7 ven for: finra/dfl. Ar/40M &

Patented Dec. 30, 1924;

UNITED STATES PATENT OFFICE.

HAROLD D. ARNOLD, OF MAPLEWOOD, JERSEY. ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED. OF NEW YORK, N. Y.', A CORPORATION OF v YORK.

Original application filed September 3, 1915, Serial No. 48,873. Divided and this applic 28, 1919. Serial No. 285,857. 4

To all whom it mag concern:

Be it known that I, HAROLD DE 'FoREsT ARNOLD, a citizen of the United States, residing at Maplewood, in the county of Es- 6 sex, State of New Jersey, have invented certain new and useful Improvements in Electron-Discharge Amplifiers, of which the following is a full, clear, concise, and exact description.

This invention relates to electron discharge devices, and more particularly to an arrangement for and method of varying the ratio of amplification of an electron discharge amplifier.

It is an object ofthe invention to provide means whereby the ratio of amplification can be varied without varying the impedanc presented by the implifier as a whole to the impulses which are to be amplified.

' This is accomplished in the preferred form of the invention by the use of an impedance shunted across the terminals of the secondary of atransformer used to step up the voltage of the incoming ourrents. The cathode of an electron dis charge tube of the three-electrode type is I connected to one end of this impedance, and

a connection is made from the control electrode by means of an adjustable contact to a desired point on the impedance, thus varying the proportionate part of the potential drop across the impedance which is applied between the control electrode and, the cathode, and correspondingly varying the anplification in the output circuit of the tu e. I

A specific feature of my invention is the incorporation of the above described controlling arrangement in the output-input coupling between two stages of a multi-stage amplifier. With this arrangement, a single source of space current is used to energize both tubes, and in the branches of the circuit therefor are interposed filters of series inductances and shunt capacity to prevent alternating current from being bypassedtherethrough. The invention described and claimed herein is divided out of my application Serial No. 48,873, filed September 3, 1915, issued as PatentNo. 1,504,537, Au st 12, 1924. The invention claimed herein 1s related to the in- .vention claimed in my ending application Serial No. 274,750, filed February 3, 1919,

ELECTRON-DISCHARGE AMPLIFIER.

ation filed March For further details, reference maybe made to the accompanying drawings in which the single figure illustrates-diagrammatically a two stage. amplifier embodying the invention.

Referring to the drawing by reference numerals, the amplifier set comprises a tandem arrangement of two vacuum tubes 10' and 11 each having a cathode 12, a grid or control'electrode 13, and an anode 14. The cathodes 12 are maintainedin a condition of thermionic activity by currents from sources 15.

The input circuit of tube 10 comprises terminals 16, 17, adapted to be connected to a suitable source of electric impulses to be repeated, a resistance 18 bridged across the input electrodes, and a battery 19 adapted to maintain the grid electrode at a negative potential with respect'to the cathode. Current between the anode and cathode is supplied from battery orother suitable source 20, the current passing in series through the inductance 21 and the transformer primary 22. A shunt condenser 23 provides a path for the alternating current.

The transformer secondary 24 has conneoted across its terminals a resistance 25,

one end of which is connected to the cathode 1 current comprises the condenser 33 and the primary 34 of-a transformer, the secondary of which is adapted to be connected through terminals 36 and .37 to any suitable receiving circuit.

In operation, the signals or other impulses, which are repeated and amplified by the tube 10, are impressed on the resistance 25 by currents induced in the seconda coil 24. The input electrodes of the secon tube are in shunt to an adjustable part of the resistance 25, and therefore any desired proportionate part of the potential drop across the resistance may be impressed between the input electrodes, with the result that the ratio of amplification may be flow therebetween, and since the capacity of these electrodes is negligibly small, the impedance of the tube to the signals is substantially infinite. It is thus seen that at all positions of the contact 26 the impedance of the second "amplifying unit to the incomv ance 25.

While I have shown and described one embodiment of the invention, it is obvious that it may assume any desired form Within the scope of the. appended claims. For example, the first amplifying unit with its output transformer might be replaced by any suitable circuit adapted to have electric currents produced therein. Other modifications Wlll occur to anyone skilled in the art.

What is claimed is:

1. In combination, an electron discharge relay comprising an anode, a cathode and a control electrode, a circuit containing a source of alternating current electric impulses to be relayed, an impedence in shunt to said source, and means comprising a contact movable along said impedence for eflectively connecting said control electrode and said cathode across an adjustable proportion of the whole of said impedance.

2. In combination, a vacuum tube repeater, an input transformer therefor, an impedance connected across, the terminals of the transformer secondary, a connection from said impedance to an electrode of said vacuum tube, and a connection from a point intermediate the ends of said impedance to another electrode of said vacuum tube.

3. In combination an electron discharge relay having an ano e, a cathode and a control electrode, a circuit containing an impedance, means for producing alternating voltage across the whole of said impedance, and means comprising a contact movable along said impedance for effectively connect ing said cathode and control electrodes across an adjustable proportion of the whole of said impedance.

4. The combination of an incoming line, an amplifier having-a cathode and an anode,

means for supplying a space current between said electrodes, said amplifier having a grid electrode for controlling such space current, means for making said grid negative with respect to said cathode, andmeans between said line and the input electrodes for makmg the impedance of said amplifier as seen from said line substantially of a constant impulses has substantially a constant a lue, namely, that""of the finrte res1st-- aeaaeea value, said last mentioned means comprising a potentiometer arrangement including an impedance and a contact movable along said impedance for varying the voltage supplied to said input electrodes.

5. A-vacuum tube repeater comprising a vacuum tube having input electrodes, an input transformer, a resistance bridged across the secondary of said transformer, a connection from one of said electrodes to said resistance, and an adjustableconnection from the other of said electrodes to a point on said resistance.

6. In combination, a vacuum tube having input and output electrodes, an electric circuit including a resistance coimected to one of saidinput electrodes, a connection from an ad'ustable contact on said resistance to the ot er of said input electrodes, means for producing an alternating current through the whole of said resistance, and means connected to said output electrodes for transmitting an amplified current of substantially the same. wave form as saidfirst mentioned current. v

7 In a'multi-stage amplifier, two amplifying stages each including an electron discharge amplifier, a coupling between said stages comprisin a resistance efiectively in the output circuit of one amplifying unit, a connection from said resistance to an electrode of the succeeding amplifying unit, and a contact movable along said resistance and connected to another electrode of said succeeding amplifying unit.

8. In a multi-stage vacuum tube amplifier, two vacuum tubes each having a cathode, an anode,1and a control-electrode, a circuit con taining a resistance effectively connected to the cathode and anode of one of said tubes,

a connection from said circuit to the cathode of the other of said tubes, and a contact movable along said resistance and connected to the control electrode of said last mentioned tube.

9. In a multi-stage vacuum tube amplifier, two vacuum tubes each having input and output electrodes and a coupling therebetween comprising a transformer having its primary connected to the output electrodes of one of said tubes, a resistance connected across the .secondar of said transformer, a connection from said resistance to an inut electrode of the other of said tubes, an a connection from an. adjustable point on said res1stance-to the other input electrode of 11. The method of operating a vacuum tube amplifier which comprises, suppl ing alternating current to be amplified, an varying the ratio of amplification while the rent to be amplified, maintaining the impedance opposed to said alternating current substantially constant and varyingthe ratio of amplification by applying a selected part of the potential of said alternating current to said input electrodes.

13. The method of operating a vacuum I tube amplifier, which comprises supplying alternating current to be amplified, varying the ratio of amplification while maintaining the impedance opposed to said alternating current substantially constant and transmitting a current through the output circuit having substantially the same wave form as that of the incoming current.

14. The method of operating a vacuum tube amplifier having input electrodes which comprises supplyin alternating current to be amplified, changing the potential of said current at a fixed ratio of transformation, and applying a selected proportionate part of the otential of the transformed current to said input electrodes.

15. The combination of an incoming line,

an electron dischargev relay of the threee'lectrode type, a transformer coupling said line to said relay, one coil of said transformer being inductively connected to the input electrodes of said relay, and a potentiometer arrangement in shunt to one ofthe coils ofsaid transformer, said potentiometer arrangement comprising an impedance and a contact movable along said impedance for varying the voltage applied to said input electrodes without materially varying I the impedance facing said line.

In' witness whereof, I hereunto subscribe my name this 26th day of March, A; D. 1919.

' HAROLD D. ARNOLD. 

